Process for producing yeast



Patented Mar; 26, E923.

UNHTED stares cornice;

than? MARTIN NILSSON AN'D NORMAN S, HAREISGH, E HEW YQBK, ASSIGNOES TO THE FLEISCHMAN'N COMPANY, GE NW YUIBZK, Iii. E, A GUREPQEATKQH OF OHIO.

rnocnss ron rnonncnre No Drawing.

'To all whom it may 00nc'em:

Be it known that We, MARTIN NILssoN, a citizen of the United States, and NORMAN S. HARRISON, a subject of Great Britain, residing, respectively, in Peekskill,*county of Westchester, and State of New York, have invented new and useful Improvements in Processes for Producing Yeast, of which the following is a full, clear, and exact specification.

Our invention relates to processes for the production of yeast and refers particularly to a process for the production of bakers yeast from sacchariferous materials, such as molasses.

The object of our invention is the a.

vision of a process for producing yeast with relatively high yields by growing it from seed yeast in a sacchariferous nutrient solution treated with yeast nutrient compounds, such solution being adapted for use in the art ofyeast manufacture instead of cereal worts.

" The usual procedure heretofore practiced in the production of yeast involved mashing malted cereals with. water at certain temperatures in order to obtain a maximum amount of carbohydrates, proteins and mineral matters in'solu-tion. The resultingniash or wortwas then filtered and the liquid stocked with-yeast, after which it was aerated to promote the growth of yeast. The

yeastthus produced was separated from the liquid by some suitable'means. 'lllhe process involvingjthis procedure, however, is a com- 'paratively'expensive one as it requires a considerable amount of coal, labor and time incident 'to its proper practice, whilefthe' delicacy. of the various operations-requires careful andexpert attention; -The process of our invention avoidsthese difiicultiesand presents a 'sinipiified pro- Y cedure whereby asuperiorxgrade oi-yeast creased ields.

" greater'certainty of results, andfiwith incan be produced moreeconomicaily with In the practice of the processed in I ventions yeast is p p gated in as'acchariierous'nutrient solution to, which has been added compounds containing phosphorus, and nitrogen in yeast assimilable form, the propagationof yeast being allowed to proceed to-the fullestdesired extent, dependent upon the qualityof yeast to be produced,

The compounds containing phosphorus Application filed January 7, 1919. A Serial Wo. 27%),62'53.

' intended to inciude those which are adapted to supply inorganic nitrogen in yeast assimilable form; those preferably employed are aninioniacai compounds, as, for example, aqua-onia (ammonium hydroxide) and salts of ammonium.

@ertain alkaline compounds in this process, however, are the equivalent of aquaanimonia when used with the addition of a suitable nitrogenous compound, as, for example, sodium hydrate, to which has been added ammonium phosphate. in the use of ammonium salts it is preferable always to add an aihali, as, for example, a carbonate or a hydrate, in order that free hydro xyl ions may be supplied while neutralizing the deleterious acidity developed during the period of yeast propagation. The second mentioned class of compounds would therefore incinde alkaline compounds. when used in this manner.

The sacchariferous material employed in the nutrient solution is of a charac ter adapted to he suhjectto fermentation under the conditions oi yeast propagation;

among those which it is contemplated using are beet molasses and cane moiasses.

harticuiarly raiuable results are obtained by the use of beet molasses with the addition of a phosphate, such as ammonium phosphate, and ammonia; the yeast which is produced has greatstrength and improved lastang qualities, the cost of propagation being inuch less than that incident to the producerally employed.

Some yeasts, as is well known, are of such character that when exposed in masses for a short time tendto break down; when this is extreme they tend .to pass into a slimy condition. By our process, however, a prod-' uctis'ohtained which does not become slimy or deteriorate with age, and has therefore tion oi? yeast by the processes heretofore genwhat has been above referred to as lasting qualitibs, such qualities insuring that a mass of yeast will sustain its strong condition for ,increased yields of a superior quality of yeast at a cost considerably below that grown from cereal worts. The sacchariferous material here employed is, however,

deficient in these constituents, which deficiency is compensated for by the added compounds.

We have found that while yeast may be produced from cane molasses by our process, it is preferable to use beet molasses, as the yeast obtained from it is'stronger, whiter,

V purer, more lasting, more easily manufactured and even less expensive that that produced from cane molasses.

By the process of this invention yeast can be propagated in a nutrient solution containing molasses, whether it be acid or,

alkaline, during the period of yeast growth, but we prefer that the condition of the nutrient solution be that of approximate neutrality since this condition appears to be conducive to. maximum -yeast. production, though it is known that yeast multiplication is carried on most thoroughly when the nutrient solution is slightly acid. The

- acidity of the solution, however, if allowed torise, will soon reach a point where the multiplication of yeast cells is deleteriously eflected. On the other hand, if the solution is too strongly akaline there will be a cessation .of yeast development, though not necessarily a cessation of the roduction of alcohol, it being known that t e production of alcohol is dependent upon the presence of zymase and is therefore not directly commensurate with yeast multiplication.

The acidity which develops while yeast is multiplying is additive to the slight initial acidity preferably maintained for economic yeast culture, such acidity bein produced by the partial assimilation of t e salts in a solution during the process of yeast propa- '60 gation, which results in releasing acid radicals or components as, for example, the

' partial assimilation --of ammonium phosphate by yeast results in releasing the radical of phosphoric acid. It is for the purpose of rebinding the acidv radicals thus released so as to restore the original conditions approximating neutrality as far as possible that compounds adapted to supply hydroxyl ions'are added to the nutrient solution. g I

The following is an example of the process of our invention 560 pounds of practically neutral beet-molasses are diluted with 950 gallons of water and a solution of 14 pounds of phosphate of ammonium is' gradually added; 11.2 pounds "of yeast are then introduced. Air is blown into the mixture until the production of yeast is ended, the mixture being maintained in a practically neutral condi-- tion by the addition of" ammonia from time to time to accomplish this result. The mixture is maintained at a temperature of 25- 30 C. during the operation which usually. occupies about 24 hours. The yeast is then separated from the remainder of the mixture in any suitable manner. The process produces from 50%-60% of an extremely strong yeast which is not nearly as subject to deterioration as is the yeast produced in the ordinary Way. 4

While the example given employs only one phosphorus-containing compound, a mixture of several phosphorus containing compounds may be used as a mixture of phosphate of ammonium and acid-phosphate of calcium.

We do not limit ourselves to-the particular compounds, quantities',,temperatures, duration of reaction or mode of procedure described, all of which maybe varied without going beyond the scope of our invention as described and claimed. 7

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

1. A process of producing yeast, which comprises preparing a yeast nutrient solution, propagating yeast therein with aeration, said yeast nutrient solution containing only molasses and inorganic compounds containing phos horus and nitrogen, which are adapted to yield at least a portion of their content to the yeast and to set free components which tend increasingly to acidify the solution during propagation, and during the period of propagation neutralizing the excess of such acidity.

2. A process of producing yeast, which comprises preparing a yeast nutrient solution, propagating yeast therein with aeration, said yeast nutrient solution containing only molassses and phosphate of ammonium adapted to be at least partially assimilated by the yeast and to set free -components which tend increasingly to acidify the solution during propagation, and during the period of propagation neutralizing the cess of such acidity.

3. A process of producing yeast, which riod of propagation racers? comprises preparing a yeast nutrient solution, propagating yeast therein with aera; tion, said yeast nutrient solution containing essentially molasses and inorganic compounds containing phosphorus and adapted to yield at least a portion of their content to the yeast and to set free components which tend increasingly to acidify the solution during propagation, and introducing into the solution during the period of propagation a compound, containing inorganic nitrogen in yeast assimilable form and having an alkaline reaction, in quantities adapted to new tralize the excess of such acidity. v

4:. A process of producing yeast, which comprises preparing a yeast nutrient solution, propagating yeast therein with aeration, said nutrient solution containing essentially molasses and phosphate of ammonium adapted to be at least partially assimilated by the yeast and to set free components which tend increasingly to acidity the nutrient solution during propagation, and introducing into the solution during the pea compound, containing inorganic nitrogen in yeast assimilable form and having an alkaline reaction, in quantities adapted to neutralize the excess of such acidit 5. 1 process of producing yeast which comprises preparing a yeast nutrient solution, propagating yeast therein with aeration, said yeast nutrient solution containing essentially beet molasses and inorganic compounds containing phosphorus and adapted v to yieldat least a portion of their content to the yeast and to release components which tend increasingly to acidity the nutrient solution during propagation, and introducing into the nutrient solution an ammoniacal compound, adapted to supply inorganic nitrogen in yeast assimilable formand having in amounts sufiicient to neutralize the excess of such acidity.

6. A; process of producing yeast which comprises preparing a yeast nutrient solution, propagating yeast therein with aeration, said yeast nutrient solutioncontaining essentially beet molasses and phosphate of ammonium adapted to .yield at least a portion of its content to the yeast and to release 7 components which tend increasingly to acidify the nutrient solution during propagation, and introducing into the nutrient solution during the period of propagation aquaammonia in amounts suflicient to neutralize the exccssof such acidity.

7. In the art of yeast manufacture, the

I process which comprises preparing in'a fermentora yeast nutrient solution, containing essentially beet molassesand inorganic-cornpounds adapted to supply phosp orus and nltrogen. and to release components which tend increasingly to acidify the solution during propagation, seeding the solution which tend increasingly to acidity the solution during propagation, introducing seed yeast, efl'ecting propagation with aeration at a temperature between the limits of 25 to 30 C., introducing into the fermentor aquaammonia in such quantities as to neutralize substantially the excess of said acidity, and thereafter separating the yeast.

9. A process of producing yeast, which comprises preparing a yeast nutrient solution, propagating yeast therein with aeration, said yeast nutrient solution containing only molasses and an inorganic compound containing phosphorus and nitrogen, which is adapted to yield at least a portion of its content to the yeast and to set free components which tend increasingly to acidffy the solution during propagation, and during the period of tralizing the excessof such acidity,

10. A process of producing yeast, which comprises preparing a yeast nutrient solution, propagating yeast therein with aeration, said yeast nutrient solution containing. essentially molasses" and an inorganic compound containing phosphorus and adapted to yield at least a portion of its content to the yeast and to set free components which tend increasingly to acidify thesolution during propagation, and introducing into the solution during the period of propagation a compound, containing inorganic nitrogen in yeast assimilable form and having an alkaline reaction, in quantities adapted to neutralize the excess of such acidity.

11. A process off producing yeast which comprises. preparing a yeast nutrient solution, propagating yeast therein-with aeration, said yeast nutrient solution containing essentially beet molasses and an inorganic compound containing phosphorus and adapted to yield at least a portion of its content to the yeast and to release components which tend increasingly to acidify the nutrient solution during propagation and introducing into the nutrient solution an ammoniacal compound, adapted to supply inorganic nitrogen in yeast assimilable form and having in amounts suflicient to neutralize the excess of such acidity.

propagation neuan alkaline reaction,

' commercial yields of'yeast, consisting of escontaining prosphorus and nitrogen in yeast sentially Water, molasses and an admixture of yeast IlOIlI'lShlHg morganic compounds assimilable form, in amounts siificient to supply all essential yeast nutrients during the propagating period.

14, In the art of manufacturing bakers yeast the step which comprises preparing ayeast nutrient solution, adapted for ;large commercial yields of yeast, consisting of essentially water,'beet molasses and ammonium phosphate, in amounts'suflioient to supply all esential yeast nutrients during the propagating period.

Signed at New York city, in the county of New York and State of New York, this 3rd day of January, 1919.

MARTIN NILSS ONQ NORMAN s. HARRISON. 

